In today's world, a digital television (TV) set presenting high-quality pictures via a digital TV broadcast signal is gradually gaining popularity. The digital TV broadcast signal received by the digital TV set contains not only digital video and audio data but also intermittently inserted PSI to provide a variety of information about broadcast programs. The PSI is also referred to as PSIP (Program System Information Protocol).
The digital TV set selects a channel, then separates and decodes digital stream of the selected channel to match pictures and sound with reference to the intermittently received PSI.
In the meantime, a high-density disk device, being developed to reproduce a HDVD with its recording standard under discussion, is expected to be connected to a digital TV set through IEEE 1394 standard as shown in FIG. 1. However, when receiving and presenting the data stream from the disk device 100, the digital TV set 200 still requires PSI to select the data stream and to control presentation of the selected data stream.
Therefore, when the disk device 100 reproduces MPEG-formatted data stream recorded on a HDVD and sends it to the digital TV set 200 connected through a digital interface such as IEEE 1394 standard, it must provide a PSI. For a digital TV set 200 in the format of transport stream (TS) consisting of 188-byte-long transport packets (TPs), a PSI may consist of a program association table (PAT), a program map table (PMT), a conditional access table (CAT) and so forth as shown in FIG. 2.
To periodically feed the digital TV set with PSI for recorded data stream via a digital TV broadcast signal, the PSI is recorded dispersedly and repeatedly in a data recording area (i.e. ‘AREA 1’) on a HDVD as shown in FIG. 3, and the repeatedly written PSI is retrieved and transmitted sequentially along the data stream.
However, if PSI is recorded dispersedly and repeatedly on a data recording area of a disk, the recording area for a real data, namely video and/or audio data, is greatly reduced, decreasing the recording efficiency of a disk.
In addition, the digital TV set cannot present the received data stream until it receives PSI retrieved in regular sequence from the PSI recorded dispersedly in the data recording area. This is despite the fact that data reception is resumed after a reproduction point is moved according to a key command of a user or a digital interface, such as after the IEEE 1394 standard is reset. Because the digital TV set cannot select data stream to decode real pictures and/or sound until the PSI, which is prepared for the data stream, is received inevitably there is a temporary discontinuity in video and/or audio.
In the meantime, the digital TV set determines when to decode and present TPs received based on PCRs (Program Clock References) intermittently in the TPs. Thus, if PCRs are discontinuous, errors might occur in decoding and presenting received TPs. Accordingly, to prevent such possible malfunction, PSI time information must be in sync with the PCRs. PCRs are included in consecutive TPs and contain real data when PSI is converted to TPs and inserted into TS of real data.